This is normally only possible on a par 3 hole. Longer hitters have accomplished this feat on shorter par 4 holes. However most par 4 holes as well as par 5 holes are too long for most golfers to reach in a single shot.

Holes in one are extremely rare, and while it depends largely on the golfer's skill, many instances have been recorded when a ball has caromed off a tree, a bird in flight, or even a passing car, before settling into the hole. Amateur players who make a hole-in-one in a friendly game will usually be mentioned in the local newspaper's sports section, provided there was at least one witness. In addition, it is customary at many clubs for the golfer to celebrate the feat by purchasing a round of drinks for fellow club patrons.

(Source Wikipedia)